1. Department of Chemistry, Graduate School of Science and Engineering, Waseda University/PRESTO-JST, Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan, Computer Center, Tokyo Metropolitan University, 1-1 Minami-Ohsawa, Hachioji, Tokyo, 192-0397 Japan, and Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan